Abstract Gas-phase hydrogenation of acetonitrile was investigated using nickel black and nickel deposited on MgO, Al 2O 3, Cr 2O 3, SiO 2, TiO 2, ZrO 2, ThO 2 and UO 2, at ambient pressure and 70 °C. Metal surface areas were measured by hydrogen chemisorption. Both reaction selectivity and catalytic activity are affected by support nature. Nickel black, Ni/MgO, Ni/ThO 2 and Ni/UO 2 catalysts have the highest selectivity to monoethylamine (>80 mol%), while Ni/TiO 2 catalysts the least (<20 mol%). All supports increase the catalytic activity of the metal surface area unit (i.e. the intrinsic activity) compared to that of the nickel black. The most efficient is TiO 2, which increases the intrinsic activity by about 20 times and the least efficient are MgO and SiO 2, with an increase of only 1.5 times. It is assumed that the role of the support is to create new active sites at the metal-support frontiers. The catalytic behavior of the Ni/Al 2O 3 and Ni/Cr 2O 3 catalysts, treated at temperatures between 350 and 1050 °C, confirms the role of the metal-support frontiers in the enhancement of the catalytic activity in acetonitrile hydrogenation.